Because food trashes contain high moisture contents and are easily rotten, it is difficult to treat them in reclamation and incineration. Therefore, these food trashes are collected together, and the collected food trashes are specially, physically and chemically processed, to thereby attempt to obtain waste reduction or try to recycle the food trashes into resources.
However, household food trash processing devices which are arranged in respective home kitchens have been recently developed for the convenience of the apartment house dweller or the old and the weak, and are widely prevailed. These household food trash processing devices reduce volume of food trashes in minimum size by passing through dehydration, crush, high-temperature dry, fermentation, decomposition, etc. and discharge the minimized volume of the food trashes.
These household food trash processing devices generate a massive amount of exhaust gas including an offensive odor that happens at the time of fermentation and decomposition of organic matters that occupy most of food trashes. Accordingly, in the case that these household food trash processing devices are mobile, it is essential to install a deodorization device to deodorize an offensive odor compulsorily in an exhaust unit. Meanwhile, in the case that these household food trash processing devices are fixed, exhaust gas is discharged through a drain.
A deodorization method using microbes, an activated carbon absorption method using activated carbon and an oxidation catalyst combustion method using an oxidation catalyst are used for conventional deodorization devices.
The microorganism deodorization method requires for a long process time, needs a persistent optimum condition to use microorganism, and requires for a periodic control. Meanwhile, since the activated carbon absorption method requires periodic replacement of activated carbon per 2 or 3 months and requires much process time, it is suitable to a small capacity device having less exhaust gas.
The deodorization method that uses an oxidation catalyst removes an offensive odor by making exhaust gas passing through a honey comb support that has a number of hollow cells in which a catalyst has been coated. Here, a heater is provided in a deodorization device so that the catalyst can react effectively with a material that induces an offensive odor, and thus heats a catalyst support at a catalyst activity temperature. The deodorization method that uses this catalyst may be used semi-permanently, and may be applied to a place where a processing capacity is big because the processing speed is high.
In the case of the deodorization device that uses the oxidation catalyst, the heater may be divided into a direct heating system in which a heater is integrally formed with a support, and an indirect heating system in which a heater is separated from a support by a predetermined distance.
As illustrated in FIG. 1, a conventional deodorization device 1 employing an indirect heating method includes an entrance 12 and an exit 14 at both sides of the conventional deodorization device 1. The conventional deodorization device 1 has a structure that a heater 16 is arranged at the entrance side of a cylindrical housing 10 which has a flow path 11 through which exhaust gas passes therein, and a honey comb support 18 having a structure of a number of hollow cells on the surfaces of which a catalyst has been coated is arranged at the rear end of the heater 16.
In the case of the conventional deodorization device 1, exhaust gas including an offensive odor passes through a number of hollow cells of a honey comb support in which the catalyst has been coated, at a state where the honey comb support 18 having a number of hollow cells in which the catalyst has been coated is heated by a heater 16 up to a catalyst activation temperature, for example, at 300-450° C., and the exhaust gas reacts with the catalyst for combustion. Accordingly, the deodorized exhaust gas is discharged via the exit 14.
In the case of the conventional deodorization devices of the above-described structures, a “U” shaped heater is disclosed in the Korean patent laid-open publication No. 2001-39702, a conical coil shaped heater which are converged consecutively from upstream to downstream is disclosed in the Korean patent No. 499725, and a coil shaped heater is disclosed in the Korean patent No. 775907. In addition, the Japanese patent laid-open publication No. 10-66953 discloses a structure that platinum supported catalyst honey comb supports are arranged in two stages in a protective tube and a bar type platinum supported heater is arranged at the front end of the platinum supported catalyst honey comb supports, respectively.
However, in the case that the above-described heaters are arranged at the rear end of the support where catalyst has been coated, the rear end of the support does not reach the catalyst activation temperature. As a result, there is a problem that effective deodorization is not achieved. Even if the rear end of the support is heated by the heater so that it may reach the catalyst activation temperature, unnecessary power consumption increases.
Meanwhile, a conventional deodorization device employing a direct heating method is disclosed in the Korean patent laid-open publication No. 2003-86085, in which a heater is arranged at the center of a spiral plate on which a metal catalyst has been coated. However, the support structure has a problem that a surface area that exhaust gas contacts is relatively smaller than that of a honey comb support structure.
As described above, the deodorization device using the heater of the indirect heating method in the catalyst support of the honey comb structure has advantages that a surface area on which a catalyst has been coated is large and introduced exhaust gas may be heated in advance, but has disadvantages that a contact time when the introduced exhaust gas contacts the catalyst is not enough in the case that velocity of a flow is fast, and thus the introduced exhaust gas is not oxidized (decomposed) or an energy efficiency drops. Meanwhile, the deodorization device using the heater of the direct heating method in the disc shaped support having a spiral plate or a partial opening portion has advantages of a simple structure and a low ventilation resistance but has disadvantages that a surface area on which a catalyst has been coated is small and introduced exhaust gas may not be heated in advance.
In addition, a low capacity heater may not be used in a general deodorization device fundamentally, and it is hard to minimize electric power consumption required for driving the heater. As a result, the general deodorization device may cause a large amount of electric power consumption, and make temperature of the exhaust gas exhausted into the indoor reach at 150-380° C.
Therefore, in the case of the conventional deodorization device of the indirect heating method or direct heating method having the above-described honey comb support structure, temperature of the exhaust gas exhausted into the indoor after having reacted with a catalyst is high if gas introduced into a deodorization chamber is heated at high temperature, for example, at 300-450° C. which is a catalyst activation temperature. Accordingly, the conventional deodorization device essentially requires that the temperature of the exhaust gas exhausted into the indoor should be lowered at temperature not more than 50° C.
As a result, according to the conventional art, an additional heat exchanger including a suction fan motor, an outdoor air inhalation unit, a condenser, etc., is installed in order to lower temperature of the indoor exhaust gas. However, since the electric power consumption of the heater is not reduced, electric power consumption of the suction fan motor for inhaling the outdoor air is not reduced.
Meanwhile, the conventional deodorization device has a structure that the catalyst support of the honey comb structure is formed of a metal thin plate, and is assembled in a manner of a brazing etc., in the inside of a housing which forms a deodorization chamber after being assembled with the heater. Therefore, the conventional deodorization device has a structure that it is hard to replace or recycle a catalyst support according to need.
In addition, hazardous substances such as carbon monoxide (CO) and nitrogen oxide (NOx) are included in the exhaust gas exhausted from vehicles, and thus a support converter for purifying exhaust gas is provided at the rear end of a vehicle exhaust manifold in order to remove hazardous substances from the exhaust gas by a perfect combustion method and discharge the purified exhaust gas.
Since temperature of exhaust gas may not reach temperature sufficient for performing a catalytic reaction in a support converter, at the initial time when a vehicles engine starts, an additional separate heater should be provided, or a support converter should be located near the engine in order to heat the catalyst support at the catalyst activation temperature quickly. Otherwise, the conventional deodorization device may use various methods of employing a catalyst converter such as a Close Coupled Catalytic Converter (CCC) where two or more supports are made close to one another.